Shooter games are a subgenre of action game, which often test the player's speed and reaction time. It includes many subgenres that have the commonality of focusing on the actions of the avatar using some sort of weapon. Usually this weapon is a gun, or some other long-range weapon. A common resource found in many shooter games is ammunition. Most commonly, the purpose of a shooter game is to shoot opponents and proceed through missions without the player character dying.

The player usually views the events from behind the eyes of the character (a first-person shooter) or from a camera that follows the character, usually a few feet behind (a third-person shooter). It is also possible for a game to have a fixed camera, especially shooting gallery games and some 2D overhead shooters such as Robotron 2084.

While most shooters are played as solo ventures, several offer the players the opportunity to control a squad of characters, usually directly controlling one, and giving orders to computer-controlled allies. Games which feature non-player characters fighting alongside the player, but which are not directly controllable (either by switching player control, or issuing orders to the character) are not considered squad-based games.

If a shooter game is playable online, there are several other sharp divisions it can take. Many games will offer differing modes which allow players to choose from among various types, such as the following. In team modes, players are assigned to one of two (sometimes more, but very infrequently) factions which are competing for some goal. Co-op modes have several players on the same faction playing through either single-player or custom missions against computer-controlled enemies. Individual (often called deathmatch) has all players competing with each other.

This is often an optional way to categorize a shooter, but in some cases it's needed to help distinguish it. A game may quite often heavily rely on stealth as opposed to direct action. Others might have large horror elements to them. However, the one thing in common with all shooters is that combat with a gun or similar long range/projectile weapon is the primary focus of gameplay itself.

Shooting gallery games include light gun games, although many can also be played using a regular joypad and an on-screen cursor to signify where the bullets are being aimed. When these debuted, they were typically played from a first-person perspective, with enemy fire that occurred anywhere on the screen damaging or killing the player. As they evolved away from the use of light guns, the player came to be represented by an on-screen avatar, usually someone on the bottom of the screen, who could move and avoid enemy attacks while returning fire. These sorts of shooters almost always utilize horizontal scrolling to the right to indicate level progression, with enemies appearing in waves from predestined locations in the background or from the sides. One of the earliest examples is the 1985 arcade game Shootout produced by Data East.

A specific subgenre of this type of game is the Cabal shooter, named for the game Cabal, in which the player controls an on-screen avatar that can run and often jump around the screen in addition to being able to aim their gun. Other games in this subgenre include Blood Bros., Dynamite Duke, NAM-1975, Wild Guns, and Sin and Punishment.

Light gun shooters are shooting gallery games that use a pointing device for computers and a control device for arcade and video games. The first light guns appeared in the 1930s, following the development of light-sensing vacuum tubes. It was not long before the technology began appearing in arcade shooting games, beginning with the Seeburg Ray-O-Lite in 1936. These early light gun games used small targets (usually moving) onto which a light-sensing tube was mounted; the player used a gun (usually a rifle) that emitted a beam of light when the trigger was pulled. If the beam struck the target, a "hit" was scored. Modern screen-based light guns work on the opposite principle—the sensor is built into the gun itself, and the on-screen target(s) emit light rather than the gun. The first light gun of this type was used on the MIT Whirlwind computer, which used a similar light pen. Like rail shooters, movement is typically limited in light-gun games.

Doom, one of the early games that defined the first-person shooter genre.

First-person shooters are characterized by an on-screen view that simulates the in-game character's point of view. While many rail shooters and light-gun shooters also use a first-person perspective, they are generally not included in this category.

Shooter games have been accused of glorifying and promoting violence and several games have been the cause of notable video game controversies. After school shootings in Erfurt, Emsdetten and Winnenden, German conservative politicians accused violent shooter games, most notably Counter Strike, to incite young gamers to run amok.[4] Several attempts were made to banish the so termed "Killerspiele" (killing games) in Germany and the European Union.[5][6] Shooter games were further criticised when Anders Breivik claimed he used a Call of Duty game to gain target acquisition.[7]